Introducing a helper wrapper for YUV-to-RGB convertion and/or scaling.

media/base/yuv_convert.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This webpage shows layout of YV12 and other YUV formats
 // http://www.fourcc.org/yuv.php
 // The actual conversion is best described here
 // http://en.wikipedia.org/wiki/YUV
 // An article on optimizing YUV conversion using tables instead of multiplies
 // http://lestourtereaux.free.fr/papers/data/yuvrgb.pdf
@@ skipping 317 matching lines @@
   }
   int source_top = dest_rect_top * y_step;
   if (y_step < kFractionMax * 2) {
     source_top += ((y_step - kFractionMax) / 2);
   } else {
     source_top += kFractionMax / 2;
   }
 
   // Determine the parts of the Y, U and V buffers to interpolate.
   int source_y_left = source_left >> kFractionBits;
-  int source_y_right = (source_right >> kFractionBits) + 2;
-  DCHECK(source_y_right <= source_width);
+  int source_y_right = std::min(
+      (source_right >> kFractionBits) + 2,
+      source_width + 1);

[Wez, 2012/02/03 22:40:35]

Not sure why this needed to change?

[alexeypa (please no reviews), 2012/02/03 23:29:35]

Because I hit this DCHECK on a legitimate call (Yuv2Rgb unit test hits it).
Because of +2 above the function can overrun the Y buffer. You can see that the
same guard for UV buffers.

 
   int source_uv_left = source_y_left / 2;
   int source_uv_right = std::min(
       (source_right >> (kFractionBits + 1)) + 2,
       (source_width + 1) / 2);
 
   int source_y_width = source_y_right - source_y_left;
   int source_uv_width = source_uv_right - source_uv_left;
 
   // Determine number of pixels in each output row.
@@ skipping 184 matching lines @@
     else
       convert_proc = &ConvertYUVToRGB32_C;
   }
 
   convert_proc(yplane, uplane, vplane, rgbframe,
                width, height, ystride, uvstride, rgbstride, yuv_type);
 #endif
 }
 
 }  // namespace media